Boylston Street Fishweir

Reports written in 1942[1] and 1949[2] describe what was thought to be remains of one large fishweir, 2,500 years old, made of up to 65,000 wooden stakes distributed over an estimated 2 hectares (4.9 acres) of the former mud flat and marshland in what is now the Back Bay section of Boston.

Fish weirs in shallow estuaries water, or in small streams, may be built with 1-to-3-inch-diameter (2.5 to 7.6 cm) vertical stakes and the horizontal structure, called wattling, made of brushwork to form a rough barrier at mid-tide depth.

[6] Fish weir discovery continued in 1939, with archeological investigations led by Frederick Johnson during foundation excavation for the New England Mutual Life Building at 501 Boylston Street.

Long sequences of wooden stakes, buried under tidal silt and an additional 15 to 20 feet (4.6 to 6.1 m) of 19th-century Back Bay fill, were found passing through the site and continuing on under surrounding streets.

Drawings and models were made based on the findings and show the fish weir built in deep water, maintained by men working from mishoons (log canoes).

Radiocarbon dating, refined pollen sample analysis, and accurate surveys allowed the fish weir stakes to be understood to straddle many different stratigraphic layers.

[8] Research on climate change and evidence from study of fish weirs and sediments under the Back Bay indicate the ocean level in the Boston area has risen more than ten feet in the last 6,000 years.

Analysis of tree rings and bark of recovered fishweir stakes reveals that the wood was often cut in the late winter and construction work on the weirs undertaken in the spring.

More research is needed to assemble a complete and comprehensive study of the fish weir history and to more fully understand the life of the early people who lived for thousands of years in the place we now call Boston.